Particulate detergent compositions comprise detersive active ingredients. Oftentimes these detersive ingredients make the particles ‘sticky’. This has the effect of making the particles stick together which negatively impacts the flowability of the granular composition and can affect the dissolution in the wash liquor. Therefore, a ‘bulking agent’ in the form of a separate particle or powder is often added to the granular composition to counteract the stickiness and maintain good flowability.
Sulphate is often used as a bulking agent. However, upon addition to the wash liquor, sulphate rapidly sinks and forms a sediment at the bottom of the container as it has a very high bulk density. Consumers associate this sedimentation with ‘poor cleaning’ as they believe that the composition is not dissolving into the water and so ‘not working’. Furthermore, in a fabric hand washing context, the slowly dissolving sediment makes the wash liquor feel ‘gritty’. Consumers associate this with ‘dirty wash water’ and ‘lack of cleaning’. In addition, as the slowly dissolving sulphate sediments in the wash liquor, it can trap other detergent components and so affect the overall cleaning performance.
A further problem is that the overall bulk density of the detergent composition is higher. This means that consumers tend to over- or under-dose the amount of detergent composition to add to the wash liquor.
One way to overcome this is to produce a particle comprising sulphate but wherein the particle has a lower bulk density than that of traditional sulphate particles. To achieve this lower bulk density, the particle needs to be manufactured using processes such as spray-drying or flash-drying. Spray- and flash-drying require the preparation of an aqueous slurry which is then dried to make the spray- or flash-dried particle. Sulphate added to this slurry tends to sediment out and so can cause blockages and associated issues during manufacture.
Thus, there is a need in the art for a process that at least in part overcomes the above mentioned problems.
The Inventors surprisingly found that a process for making a particle comprising at least 45 wt % sulphate, from 0 wt % to 15 wt % anionic detersive surfactant, and having a bulk density of from 350 g/l to 700 g/l, comprising the steps of; (a) preparing an aqueous slurry comprising sulphate, and optionally detersive surfactant; (b) drying the particle; and wherein the sulphate added to the aqueous slurry has a volume average particle size of from 10 micrometers to 50 micrometers overcame the above-mentioned sedimentation problem. It was also surprisingly found that when particles made using the process of the present invention were added to a wash liquor, the resultant wash liquor had a less ‘gritty’ feel.